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Vianey-Saban C, Guffon N, Fouilhoux A, Acquaviva C. Fifty years of research on mitochondrial fatty acid oxidation disorders: The remaining challenges. J Inherit Metab Dis 2023; 46:848-873. [PMID: 37530674 DOI: 10.1002/jimd.12664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 07/19/2023] [Accepted: 07/26/2023] [Indexed: 08/03/2023]
Abstract
Since the identification of the first disorder of mitochondrial fatty acid oxidation defects (FAOD) in 1973, more than 20 defects have been identified. Although there are some differences, most FAOD have similar clinical signs, which are mainly due to energy depletion and toxicity of accumulated metabolites. However, some of them have an unusual clinical phenotype or specific clinical signs. This manuscript focuses on what we have learnt so far on the pathophysiology of these disorders, which present with clinical signs that are not typical of categorical FAOD. It also highlights that some disorders have not yet been identified and tries to make assumptions to explain why. It also deals with new treatments under consideration in FAOD, including triheptanoin and similar anaplerotic substrates, ketone body treatments, RNA and gene therapy approaches. Finally, it suggests challenges for the diagnosis of FAOD in the coming years, both for symptomatic patients and for those diagnosed through newborn screening. The ultimate goal would be to identify all the patients born with FAOD and ensure for them the best possible quality of life.
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Affiliation(s)
- Christine Vianey-Saban
- Biochemical and Molecular Biology Laboratory, Metabolic Inborn Errors of Metabolism Unit, Groupement Hospitalier Est, CHU de Lyon, Bron, France
| | - Nathalie Guffon
- National Reference Centre for Hereditary Metabolic Diseases, Groupement Hospitalier Est, CHU de Lyon, Bron, France
| | - Alain Fouilhoux
- National Reference Centre for Hereditary Metabolic Diseases, Groupement Hospitalier Est, CHU de Lyon, Bron, France
| | - Cécile Acquaviva
- Biochemical and Molecular Biology Laboratory, Metabolic Inborn Errors of Metabolism Unit, Groupement Hospitalier Est, CHU de Lyon, Bron, France
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Velasco K, St-Louis JL, Hovland HN, Thompson N, Ottesen Å, Choi MH, Pedersen L, Njølstad PR, Arnesen T, Fjeld K, Aukrust I, Myklebust LM, Molven A. Functional evaluation of 16 SCHAD missense variants: Only amino acid substitutions causing congenital hyperinsulinism of infancy lead to loss-of-function phenotypes in vitro. J Inherit Metab Dis 2021; 44:240-252. [PMID: 32876354 DOI: 10.1002/jimd.12309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 08/24/2020] [Accepted: 08/28/2020] [Indexed: 12/26/2022]
Abstract
Short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD), encoded by the HADH gene, is a ubiquitously expressed mitochondrial enzyme involved in fatty acid oxidation. This protein also plays a role in insulin secretion as recessive HADH mutations cause congenital hyperinsulinism of infancy (CHI) via loss of an inhibitory interaction with glutamate dehydrogenase (GDH). Here, we present a functional evaluation of 16 SCHAD missense variants identified either in CHI patients or by high-throughput sequencing projects in various populations. To avoid interactions with endogenously produced SCHAD protein, we assessed protein stability, subcellular localization, and GDH interaction in a SCHAD knockout HEK293 cell line constructed by CRISPR-Cas9 methodology. We also established methods for efficient SCHAD expression and purification in E. coli, and tested enzymatic activity of the variants. Our analyses showed that rare variants of unknown significance identified in populations generally had similar properties as normal SCHAD. However, the CHI-associated variants p.Gly34Arg, p.Ile184Phe, p.Pro258Leu, and p.Gly303Ser were unstable with low protein levels detectable when expressed in HEK293 cells. Moreover, CHI variants p.Lys136Glu, p.His170Arg, and p.Met188Val presented normal protein levels but displayed clearly impaired enzymatic activity in vitro, and their interaction with GDH appeared reduced. Our results suggest that pathogenic missense variants of SCHAD either make the protein target of a post-translational quality control system or can impair the function of SCHAD without influencing its steady-state protein level. We did not find any evidence that rare SCHAD missense variants observed only in the general population and not in CHI patients are functionally affected.
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Affiliation(s)
- Kelly Velasco
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Johanna L St-Louis
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Henrikke N Hovland
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Nels Thompson
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Åsta Ottesen
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Man Hung Choi
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Line Pedersen
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Pål R Njølstad
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Surgery, Haukeland University Hospital, Bergen, Norway
| | - Karianne Fjeld
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Ingvild Aukrust
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Line M Myklebust
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Anders Molven
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
- Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
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Wang X, Zheng R, Yao Q, Liang Z, Wu M, Wang H. Effects of fluoride on the histology, lipid metabolism, and bile acid secretion in liver of Bufo gargarizans larvae. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 254:113052. [PMID: 31465901 DOI: 10.1016/j.envpol.2019.113052] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/12/2019] [Accepted: 08/11/2019] [Indexed: 06/10/2023]
Abstract
In our study, Bufo gargarizans (B. gargarizans) larvae were exposed to control, 0.5, 5, 10 and 50 mg/L of NaF from Gs 26 to 42. At Gs 42, we evaluated the changes of liver histology and the mRNA levels of target genes in liver. In addition, we also examined the composition and content of fatty acids. Histological analysis revealed that fluoride caused liver injury, such as the increase of number of melanomacrophage centres, atrophy of nucleus, dilation of bile canaliculus, and decrease of quantity, degradation and deposition of lipid droplets. The results of RT-qPCR indicated that exposure to 5, 10 and 50 mg/L of NaF significantly decreased the transcript levels of genes related to fatty acid synthesis (FASN, FAE, MECR, KAR and TECR) in liver. Besides, mRNA expression of genes involved in fatty acid β-oxidation (ECHS1, HADHA, SCP2, CPT2, ACAA1 and ACAA2) and oxidative stress (SOD, GPx, MICU1 and HSP90) was significantly downregulated in 0.5, 5, 10 and 50 mg/L of NaF treatment groups. Also, in the relative expression of genes associated with synthesis and secretion of bile acid, BSEP significantly increased at 0.5, 5 and 50 mg/L of NaF while HSD3B7 significantly reduced in 0.5, 5, 10 and 50 mg/L of NaF. Finally, the fatty acid extraction and GC-MS analysis showed that the content of saturated fatty acids (SFAs) was decreased and the content of polyunsaturated fatty acids (PUFAs) was increased in all fluoride treatment groups. Taken together, the present results indicated that fluoride-induced the histological alterations of liver might be linked to the disorder of lipid metabolism, oxidative damage.
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Affiliation(s)
- Xianchan Wang
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China
| | - Rui Zheng
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China
| | - Qiong Yao
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China
| | - Zhijia Liang
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China
| | - Minyao Wu
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China
| | - Hongyuan Wang
- College of Life Science, Shaanxi Normal University, Xi'an, 710119, PR China.
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Mitochondrial β-oxidation of saturated fatty acids in humans. Mitochondrion 2018; 46:73-90. [PMID: 29551309 DOI: 10.1016/j.mito.2018.02.009] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 12/04/2017] [Accepted: 02/27/2018] [Indexed: 12/30/2022]
Abstract
Mitochondrial β-oxidation of fatty acids generates acetyl-coA, NADH and FADH2. Acyl-coA synthetases catalyze the binding of fatty acids to coenzyme A to form fatty acyl-coA thioesters, the first step in the intracellular metabolism of fatty acids. l-carnitine system facilitates the transport of fatty acyl-coA esters across the mitochondrial membrane. Carnitine palmitoyltransferase-1 transfers acyl groups from coenzyme A to l-carnitine, forming acyl-carnitine esters at the outer mitochondrial membrane. Carnitine acyl-carnitine translocase exchanges acyl-carnitine esters that enter the mitochondria, by free l-carnitine. Carnitine palmitoyltransferase-2 converts acyl-carnitine esters back to acyl-coA esters at the inner mitochondrial membrane. The β-oxidation pathway of fatty acyl-coA esters includes four reactions. Fatty acyl-coA dehydrogenases catalyze the introduction of a double bond at the C2 position, producing 2-enoyl-coA esters and reducing equivalents that are transferred to the respiratory chain via electron transferring flavoprotein. Enoyl-coA hydratase catalyzes the hydration of the double bond to generate a 3-l-hydroxyacyl-coA derivative. 3-l-hydroxyacyl-coA dehydrogenase catalyzes the formation of a 3-ketoacyl-coA intermediate. Finally, 3-ketoacyl-coA thiolase catalyzes the cleavage of the chain, generating acetyl-coA and a fatty acyl-coA ester two carbons shorter. Mitochondrial trifunctional protein catalyzes the three last steps in the β-oxidation of long-chain and medium-chain fatty acyl-coA esters while individual enzymes catalyze the β-oxidation of short-chain fatty acyl-coA esters. Clinical phenotype of fatty acid oxidation disorders usually includes hypoketotic hypoglycemia triggered by fasting or infections, skeletal muscle weakness, cardiomyopathy, hepatopathy, and neurological manifestations. Accumulation of non-oxidized fatty acids promotes their conjugation with glycine and l-carnitine and alternate ways of oxidation, such as ω-oxidation.
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